1. Field of the Invention
One embodiment of the present invention relates to a memory circuit. Further, one embodiment of the present invention relates to a memory device including a memory circuit.
2. Description of the Related Art
In recent years, devices including circuits composed of only transistors having the same conductivity type (also referred to as circuits composed of only n-channel transistors or p-channel transistors) have been developed.
An example of the circuit composed of only transistors having the same conductivity type is an inverter, which is a logic gate.
For example, when the mobility is very different between a p-channel transistor and an n-channel transistor that both include a channel formation region containing the same semiconductor material, it is difficult to constitute an inverter using these p-channel and n-channel transistors. In contrast, an inverter can be easily constituted of transistors having the same conductivity type.
An example of a device including the inverter is a memory circuit (e.g., Patent Document 1).
For example, a memory circuit disclosed in Patent Document 1 is a memory cell of static random access memory (SRAM). The memory circuit disclosed in Patent Document 1 includes two switching transistors and two inverters each of which is composed of only transistors having the same conductivity type.